The Study On Fieldbus Measurement And Control Instrument Applied To Power Plant

With the rapid development of computer and communication technology, the measurement and control technology have changed deeply. At present, distributed control system (DCS) has lost its advantages in process controlling of power plant. Fieldbus control system (FCS) develops rapidly, so the traditional DCS, in which analog signal and digital signal have no correlation, must be replaced by FCS, which is more reliable and more convenient. Fieldbus control system can realize distributed measurement and control in deed.The thesis puts forward a new and practical fieldbus instrument. The instrument can receive signals put out from all kinds of usual sensors, sample and transmit the field value and realize analog and digital closed loop control. Besides the instrument can sample data in field, transmit data and control equipment in field. The popular fieldbus, PROFIBUS, is adopted in the designing of fieldbus measurement and control instrument applied for power plant, PROFIBUS protocol is used on the communication part of the instrument. So the instrument can work well together with all PROFIUBS products from other manufacturers. Compared with DCS which has same spots, the cost of the instrument is reduced remarkably. It can be applied for monitoring and controlling of small power plants and the benefit of the plants can be enlarged.At first, several popular fieldbuses around the world are introduced in the thesis. Then the fieldbus adopted in the design, PROFIBUS, is discussed in details, involving its general characteristics, functions and transmission techniques. The communication protocol and the message format of PROFIBUS are studied in emphasis. At last, the thesis designs the hardware and software of the instrument, completes the study of fieldbus measurement and control instrument applied to power plant.